A company does not have to pay more than union wages in a union state.
They are free to pay more to good workers in a right to work state and with real competition may actually do so.
Your answer is incorrect. A right to work state may still have unions and collective bargaining agreements. By federal law those agreements cover all employees that are part of the bargaining union,whether they pay union dues or non.
A right to work law does not negate collective bargaining agreements or exclude non-dues paying members from the terms of the agreement.